By Sid Perkins
On Jan. 17, 1994, about 2 hours before sunrise, a magnitude-6.7 earthquake struck Southern California’s San Fernando Valley. The temblor, which originated beneath Northridge, occurred along a previously inactive and unknown fault zone. In a quake that generated an estimated $10 billion in damages—the United States’ costliest earthquake to date—dozens of bridges collapsed, hundreds of buildings were destroyed, and 57 people died.
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Last month, that quake struck again—this time, it rumbled through a corner of a lab at the State University of New York at Buffalo. In a building the size of an airplane hangar, scientists used computer-controlled hydraulic equipment to recreate the ground motions of the Northridge quake. The team applied the tremors to a two-story wood-frame townhouse that members of a five-university consortium had constructed atop two large platforms called shake tables.